Key result
Electrophysiological mapping during AVNRT demonstrated that return cycles at the His bundle to inferior coronary sinus ostium matched the tachycardia cycle length, indicating circuit involvement (P<0.0001).
Observational (n=18)
Electrophysiological mapping using single extrastimuli demonstrates that the perinodal atrium extending from the His bundle to the inferior coronary sinus ostium is involved in the AVNRT circuit.
BACKGROUND: The exact boundaries of the reentry circuit in atrioventricular nodal reentrant tachycardia (AVNRT) have not been convincingly defined. METHODS AND RESULTS: To define the tachycardia circuit, single extrastimuli were delivered during AVNRT to 8 sites of the right intra-atrial septum: 3 arbitrarily divided sites of the AV junction extending from the His bundle (HB) site to the coronary sinus ostium (CSOS) (sites S, M, and I) and the superior (S-CSOS), inferior (I-CSOS), posterior (P-CSOS), and posteroinferior (PI-CSOS) portions of the CSOS and the CSOS in 18 patients. The mean tachycardia cycle length (TCL) was 368+/-52 ms. Retrograde earliest atrial activation was observed at the HB site in all patients. The longest coupling intervals of single extrastimuli that reset AVNRT at sites S, M, I, I-CSOS, CSOS, S-CSOS, P-CSOS, and PI-CSOS were 356+/-51, 356+/-51, 355+/-52, 357+/-51, 318+/-47, 305+/-53, 311+/-56, and 312+/-56 ms, respectively, and the following return cycles at these sites were 368+/-52, 368+/-53, 367+/-53, 367+/-53, 407+/-66, 431+/-73, 415+/-55, and 412+/-56 ms, respectively. The longest coupling intervals at sites S, M, I, and I-CSOS did not differ from each other and were longer than those at CSOS and S-, P-, and PI-CSOS (P<0.0001). The return cycles at sites S, M, I, and I-CSOS did not differ from the TCL, whereas those at CSOS and S-, P-, and PI-CSOS were longer than the TCL (P<0.0001). CONCLUSIONS: The perinodal atrium extending from the HB site to I-CSOS was involved in the tachycardia circuit. I-CSOS was thought to be the entrance of the slow pathway.
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Yamabe et al. (1999) conducted an observational in Atrioventricular nodal reentrant tachycardia (AVNRT) (n=18). Single extrastimuli mapping was evaluated on Longest coupling intervals and return cycles of single extrastimuli resetting AVNRT at 8 right intra-atrial septum sites (p=<0.0001). Electrophysiological mapping during AVNRT demonstrated that return cycles at the His bundle to inferior coronary sinus ostium matched the tachycardia cycle length, indicating circuit involvement (P<0.0001).
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